Field of the Invention
The present invention relates to a wireless power supply apparatus that supplies power wirelessly.
Description of the Related Art
Conventionally, there has been a need for further reduction of energy consumption in production equipment. In the case of production equipment that uses robots, wireless power supply is being considered to reduce wiring and the like, and to promote space-saving. In such production equipment, energy consumption in the overall production equipment can be reduced by interchanging power among loads, such as robots. In other words, a load, such as a robot, consumes energy, such as electrical power, during acceleration and conversely, generates energy during deceleration. As a result of the energy generated during deceleration being changed to electrical power and the power being consumed by another load, such as another robot, energy consumption in the overall production equipment can be reduced.
As a technique for wirelessly supplying power, a technique has been proposed in which power is interchanged bi-directionally between a power supply side and a load side (refer to Heisei 24 The Institute of Electrical Engineers of Japan Zenkoku Taikai 4-203). The premise of this technique is vehicles, such as electric cars. Therefore, wireless interchange of power is performed between the power supply side and the load side, using electromagnetic induction with a frequency band of 100 kHz or lower.
However, when the frequency band is 100 kHz or lower, a problem occurs in that the physical structure of a coil becomes larger to enable sufficient power can be supplied. In the case of a vehicle, limitation is minimal even when a physically large coil is used because the vehicle itself is sufficiently large. However, in the case of a robot in production equipment, interchange of power using a smaller coil is desired. In other words, when a large and heavy coil is used in a robot, a problem occurs in that the weight of the robot itself increases, a driving apparatus becomes larger in accompaniment with the increase in weight, and the equipment itself becomes larger.
However, to perform wireless power supply using a small coil, power supply in the megahertz frequency band is required. In a high-frequency band such as this, a problem occurs in that switching loss and the like occur when electromagnetic induction is used.